Improvement in electric fuses



UNITED STATES PATENT OFFICE.

GEORGE M; MOWBRAY. ornonrn ADAMS, MASSACHUSETTS.

IMPROVEMENT IN ELECTRIC FUSES.

, Specification forming part of Letters Patent No. 139,686, dated June 10, 1873 application filed March 19, 1873. p

To all whom it mayconcern:

Be it known that I, GEORGE M. MowBRAY, of North Adams, in the county of Berkshire and State of Massachusetts, have invented an Improved Electric Fuse-Exploder, of which the following is a specification;

The nature of my invention consists in an improved method of securing the conducting.

wires, the priming, and the fulminating-cap used for exploding nitro-glycerine, gun-cotton, dynamite mica blastiug-powder,'and other explosives whose blasting power is enhanced by the initial explosion of the priming charge. so as to avoid'the deteriorating influence aris ing from either disturbancemf their relative parts, or from heat, cold moisture, or rough handling, and at the same time to so confine the priming that is fired by the electric cur-- rent, in the presence of the fuhuinate, as to securea very heavy explosion by means of a comparatively moderate charge of said fulminate. Although I do not confine myinve n tion to guttapercha and copperbut it is equally applicable to any plastic material of good insulating properties which hardens by cooling, as this gum does, while asteel, brass, or sheet-iron shell for the shell portion of the device answers in like manner-yet in this specification,-for the sake of brevity, I shall confine my descriptiouto guttapercha in describing the insulating material, and to cop- .per for the wires and for the shell. The ductility of this latter and itsexcellent conducting properties, ,:wlri1e the easy manipulation of gutta-percha,,; its facility for molding into shape, audits property of welding, renders it, with its insulating power, well adapted for this device. Moreover, the power to resist strain is very great both in copper and guttapercha, which property is valuable in my invention.

Figure 1 shows the copper shell A and the insulating envelope B.

Fig. 2-0, the insulated wires; D, the plug containing the electric fuse-priming compositiou; A, the copper shell; B,Xthe insulating envelope. s;

Fig. 3 shows\the electrical fuse-cap .com-

vplete. A, the copper shell, which is charged with about twenty grains of the mercuric fulminate; B, insulatingenvelope; C, insulated conducting and return wire; D, insulated priuiing-plug2 The conducting and return wires are drawn to a gage of about No. 22 or so. 24, and

covered with insulation to a gage of No. 14, both English standard gages. The terminals of the wire are stripped of insulation for about half an inch. Aplug'of gutta-perchais molded so as to have a section, as shown at I); Fig. 2. A mold is prepared consisting of a, tapering tube, a pin to carry ,the copper-shell, and a piston to push out the envelope and shell when cold. With this mold an insulation of gntta-percha is for|ned,envelopin g the copper shell, which is then charged with about twenty grains of mercuric fulmiun'te. The plug D, after inserting a few grains of suitablepriming between the terminals of the copper wire, is closed with a disk of card-board,and

the flanged edge, being moistened with a solution of. gutta-percha, is immediately fitted and pressed into the insulated shell A, B, Fig. 2, forming when complete Fig. 3.

It will be observed that theinulation or the wires 0 is welded to the capping-plug l),

discharged into the nitro-glycerine with a sudlden violent explosion, so necessary to the full development of the blasting force of this explosive and others of'a kindred nature.

Having thus described my invention, what I claim, and desire to secure by Letters Patent,

isw 1. The plug D with its priming-chamber and flange, substantially as described.

' 2. The insulated copper shell A B, substantially as described.

3.- The combination of insulated wires C with the molded plug D, substantially as described.

' 4. The combination of the insulated wires 0, the plug D, and theinsulated copper shell, substantially as described.

Witnesses:

W. H. GsIswoLn, WM. K. HARLOW.

cs0. n. MOWBRAY. 

